Patent GB-714893-A (GB)
Title: Improvements in machines for trimming pieces of flexible stock
IPC: B29C37/02
Filed: 1952-07-30
Abstract: 714,893. Butt-splicing rubber tubes. UNITED STATES RUBBER Co. July 30, 1952 [Oct. 23. 1951], No. 19255/52. Class 70 [Also in Group VIII] A machine for trimming to a pre-determined length a piece of rubber tyre stock prior to splicing together the ends to form an inner tube comprises a pair of clamps for securing the end portions of the stock, means for severing the end portions of the stock extending from the faces of the clamps, and spaced means providing gauge points which are arranged to be so adjusted that the combined distance from one clamp face over said spaced means to the face of the other clamp is of such a pre-determined length that, when a piece of stock is arranged in contact with the spaced means and with its ends secured between the clamps, the severing means will form the stock to the desired length. The machine shown in Fig. 2 for both trimming the ends of a rubber tube and then splicing them together comprises two clamps each in the form of a stationary jaw 17 and movable jaw 18 operable by an air cylinder 21 and mounted on a carriage 11, the two carriages being slidable to and from each other by means of an air cylinder 14 acting through bell-cranks 15, 16. The trimming knives 24, 25 are carried by a carriage 23 movable horizontally between the carriages 11. The machine is also provided with four gauge pins 26, 27, 28, 29 over which the stock to be cut is draped. Each carriage 11 has an outwardly-projecting arm 45 on which is slidably adjustable a block 41 supporting one of the pins 26, 27, each pin being in the form of a sleeve 30, Fig. 25, rotatable on a shaft 33 fixed on an arm 37 which is carried by a shaft 40 journalled in a block 41. Each sleeve 30 'can rotate in only one direction as permitted by a spring pawl engaging a rachet wheel 34 on the sleeve, and each arm 37 is normally latched to its block 41 by a spring-pressed pin 42 engaging. a hole in the arm. The pins 28, 29 which are secured directly to the carriages 11 beneath the clamps may be either rotatable or non-rotatable. In use, the blocks 41 are clamped at such distances along the arms 45 as to position the pins 26, 27 according to the desired length of the trimmed tube, and the stock is draped around all the pins so that its ends overlap the faces of the stationary jaws of the clamps. The clamps are then closed, the knives 24, 25 operated to trim the projecting ends, and the carriages 11, 12 moved inwardly to bring the cut ends of the tube into engagement to form a splice. During this movement of the carriages, cam. bars 47 or brackets upstanding from the base 10 actuate the latching pins 42 so that the arms 37 are unlatched from the blocks 41 with the result that when after release of the clamps the carriages are retracted, the pins 26, 27 swing inwardly under the influence of the spliced tube without stretching the latter. If desired, the pins 28, 29 may be dispensed with and the stock then arranged to contact the lower faces of the stationary jaws of the clamps. In a modification for cutting tubes which have been extruded in the form of helices as described in U.S.A. Specification 2,423,147, the pins 51, 52, Fig. 9, are mounted in adjusted positions on brackets 55, 56 which extend outwardly from the carriages and have their ends bent forwardly so that the pins are disposed at an angle conforming to the angle of the helical tube section and permitting the spliced member to slip off the pins when the carriages are retracted; in this construction, the lower pins 53, 54 may be dispensed with or replaced by curved plates adjustably mounted on the base. In a further modification, a clamp consisting of a stationary jaw 66. Fig. 19, cooperating with a pivoted jaw 67 is mounted on each of two slidable carriages 63, 64 and two trimming knives 71, 72 are movable vertically by an air cylinder 73. Two pins 74, 75 similar to the pins 26, 27, Fig. 2. are mounted on arms carried by the base. being urged from their normal latched state to release position by cam bars 82 on the carriages when the latter are retracted. In this construction, the tube stock is draped over the pins 74, 75 and, a curved plate 83 arranged directly over the clamping jaws. Specification 676,860 and U.S.A. Specification 2,024.577 also are referred to.